CVE-2021-27943
📋 TL;DR
This vulnerability allows an attacker to brute-force the pairing code between Vizio Smart TVs and the mobile app, enabling remote control of TV settings. It affects Vizio P65-F1 and E50x-E1 Smart TVs with specific firmware versions, potentially impacting users who rely on the mobile app for control.
💻 Affected Systems
- Vizio P65-F1 Smart TV
- Vizio E50x-E1 Smart TV
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
An attacker gains full remote control of the TV, altering settings, accessing connected devices, or disrupting functionality, potentially leading to privacy breaches or denial of service.
Likely Case
An attacker on the same network brute-forces the pairing to change TV settings or cause minor disruptions, such as volume or input changes, without persistent access.
If Mitigated
With network segmentation or disabled pairing, the attack is prevented, limiting impact to isolated incidents if other controls like firewalls are in place.
🎯 Exploit Status
Exploitation involves brute-forcing a 4-digit code (10000 possibilities), which is trivial with automated tools on the same network.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Vizio support for updated firmware beyond the affected versions
Vendor Advisory: https://www.vizio.com
Restart Required: Yes
Instructions:
1. Navigate to TV settings. 2. Check for firmware updates in the System or About section. 3. Install any available updates and restart the TV.
🔧 Temporary Workarounds
Disable Mobile Pairing
allTurn off the pairing feature in TV settings to prevent exploitation.
Network Segmentation
allIsolate the TV on a separate VLAN or network to limit access to trusted devices only.
🧯 If You Can't Patch
- Disable the mobile app pairing functionality in TV settings to block the attack vector.
- Implement strict network access controls, such as MAC filtering or firewall rules, to restrict which devices can communicate with the TV.
🔍 How to Verify
Check if Vulnerable:
Check the TV firmware version in settings: if it matches the affected versions (6.0.31.4-2 for P65-F1 or 10.0.31.4-2 for E50x-E1), it is vulnerable.Check Version:
On the TV, go to Menu > System > System Information or similar to view the firmware version.Verify Fix Applied:
After updating, confirm the firmware version has changed to a newer release not listed as affected.📡 Detection & Monitoring
Log Indicators:
- Unusual pairing attempts or repeated failed authentication logs from the TV or network devices
Network Indicators:
- Suspicious network traffic patterns, such as rapid sequential requests to the TV's pairing port from untrusted IPs
SIEM Query:
Example: 'source="tv_logs" AND event_type="pairing_failure" AND count > 100 within 1 minute'